Shutter Precision PD-8 dynamo hub first impressions

Last winter (2011), I finally built a dynamo-hub front wheel (Shimano Alfine Hub and 26 in MTB rim) for my winter/wet commuter. I was tired of charging batteries and getting lazy, with the obvious results. The Alfine powers my 2 XML headlights and tail light (19 red LEDs) "to infinity and beyond", and all I have to do is turn 'em on and clean the lenses. I built a circuit (fits in the steer tube) that boosts output at my optimum speed and also provides an acceptable stand light (one headlight and taillight) when the bike comes to a stop. It works so well, I decided to do the same thing for my summer commuter.
While the Alfine works great, I had since read about this hub and wanted to try one.
Shutter Precision touts their dynamo hubs as the lightest, most efficient on the market. The PD-8 is a (6 bolt) disc version of its 6V3W hub intended for 26 in. or 700c wheels. As such, I assume it puts out 500 mA, and take efficiency to mean less drag, when the lights are on or off. (FWIW, on the road, I don't notice the drag from the Alfine, but less can't be bad.)
It cost $130.00 USD (including shipping from Taiwan) and arrived at my door in Canada in under 2 weeks.
I was very happy with the price, delivery, and product from the box. The QR hub (skewer not included) seems well constructed, and is certainly small and light (for a dyno-hub). The bearings are sealed, so replacement may be problematical. Time will tell.
Build-up was straightforward, while the left flange is 2 mm bigger than the right (at least on the PD-8, not really an issue). In the workstand, with tire (700 x 32c) mounted, it definitely spins more freely than the Alfine, in both modes, but the light didn't seem to come on as early.
On the road, the hub works as expected, but it does take another (3rd) pedal stroke to put out full, steady light. This system has 2 P7 headlights and 1 red XP-E taillight, and it powers them all with no noticeable drag from the hub, so I just leave them on during the day too. (The XP-E is quite effective, running near its max. At a stoplight, a motorist had to tell me how bright it was, and where could he get one? This was in broad daylight, and music to my ears.)
I've read that some dyno-hub users feel vibrations in the handlebars at certain speeds, usually above 20 kph. I believe this issue mostly arises on older (road/touring) bikes with more flexible frames and (especially) forks. I haven't noticed any vibrations on either of my bikes - both have steel MTB frames and robust straight blade forks.
After limited use, I'm very happy with this hub. It's light enough, looks good, and seamlessly powers my 2 headlights and taillight. Just remains to be seen how well it stands up to everyday use.

hi Jack.. thanks for the report.

It's always good to get some feedback on new products. I've got two wheels with Schmidt dynamos (both SON 28's), and have no plans to retire them, but can't help but be curious about the SP dynamos.

I've read the comparison of various dynamos in a recent issue of Bicycle Quarterly, and the SP dynamos did quite well. I don't recall the specifics, but it may be that the SP dynamo is designed to provide its rated power at higher speeds than the Alfine (or SON28), and that may partly explain how it spins in the truing stand.

For commuting, it really is a joy to have a good dynamo and LED lights. Like you, I leave mine on all of the time, and have received various comments about the visibility. There is a certain peace of mind that comes with knowing that you are visible, as well as being prepared for lousy weather or an unplanned need to ride at night (i.e. having to stay late at work).

Hello Steve. I've read a lot of (and learned much from) your posts since I embarked on my dynamo odyssey. Many thanks.
Apparently, the PD-8 has only 26 poles, while the Alfine has 28. I figured that accounted for the slightly slower light-up. Nevertheless, I like both of my dynos for all the reasons you pointed out. Cheers.

Hi Jack, would it be possible to post pictures of your setup?

Currently using Shimano Deore XT dynamos with 4 Cree xp-gs. Looking to get the SP and hook it up with 6 xp-g2s.

Where in Canada are you?

mrbubbles said:

Currently using Shimano Deore XT dynamos with 4 Cree xp-gs. Looking to get the SP and hook it up with 6 xp-g2s.

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Just wondering.... is your plan to wire up 6 xp-g2s in series? Or is this two parallel strings, with each string composed of 3 LEDs in series? If the plan is 6 LEDs in series, there could be trouble getting any light at slow to moderate speeds.

Steve K said:

Just wondering.... is your plan to wire up 6 xp-g2s in series? Or is this two parallel strings, with each string composed of 3 LEDs in series? If the plan is 6 LEDs in series, there could be trouble getting any light at slow to moderate speeds.

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6 in series using 2 triples with circuit #9 in the following link. http://pilom.com/BicycleElectronics/DynamoCircuits.htm

I've been using the 4 cree xp-gs for 2 years now without a voltage doubler and it works great, I added the voltage doubler on another bike but hardly ever use it. But I foresee using it a lot more with 6 leds in series.

Hi mrbubbles. Sorry, but I don't have enough posts to send attachments. I can tell you, I've wired the 3 LEDs in series, and have full light around 10 kph. (The supercap in my circuit may be a factor - don't think it completely discharges with daily use.) Steve K has much more experience with dynamos than me, but from my research, I would agree with him that 6 XP-G2s in series won't put out much light at low to moderate speed. (The SP hubs output is still only 500 mA.) If low speed performance isn't that important, you might be fine. From my limited experience with the SP hub, it's not quite as good as my Shimano Alfine in that department. By the way, I live in Toronto.

If the 6 in series is unsatisfactory I can also swap it with the Shimano and replace the SP with 4 xp-gs instead. Ordered the parts, now I just gotta wait.

I got everything setup and running, using XPE triple and a XPG triple, both gen2, on a 32 hole sp dynamo pd-8 with martin's #10 circuit. Took it out for 30km spin. In comparison to Shimano Deore XT dynamo running the same led setup, the SP dynamo required 2-3km more speed for the equivalent amount of light, thus there's no light during walking pace on the sp dynamo with the voltage doubler on (low mode).

With 6 leds, there's no need for the high mode, really really overkill, I found myself on the low mode 70% of the time, doubling the lumens doesn't translate very well to 2 times the light on the road.

Although Shimano hubs generate higher wattage at lower speed, I like the sp dynamo more, it looks better. In the future, I'd stay away from xpg triples, there just isn't any optics that can create a narrow beam for road riding compared to xp-e. If I had to do this all over again, I'd choose two triple xp-es with two narrow carclo triple optics. For city riding, I'd go for one triple xp-e spot and one single xp-g medium, 4 led in total, which is more than plenty.

The biggest drawback of these diy system is the beam pattern, a properly designed beam pattern can utilize these 6 leds very effectively. Otherwise if I wanted to forgo this diy process, I would've just bought the Dosun U1 light, and it comes with standlight and rear light wiring.

http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_nl.html#Dosun_u1

mrbubbles said:

The biggest drawback of these diy system is the beam pattern, a properly designed beam pattern can utilize these 6 leds very effectively. Otherwise if I wanted to forgo this diy process, I would've just bought the Dosun U1 light, and it comes with standlight and rear light wiring.
http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_nl.html#Dosun_u1

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I second this.
I eventually bought a Cyo to use as a 'dip' beam with a nice anti-dazzle cut-off and built my own +/-4deg light for a 'main' beam for when no one was in front of me.
It works out pretty well. You can tap into the Cyo circuits and power its led or the 'main' led.

BTW, what is the Dosun beam like. The figures say it is dimmer than the Cyo, but it might have a better spread?

The other Steve

Bandgap said:

BTW, what is the Dosun beam like. The figures say it is dimmer than the Cyo, but it might have a better spread?

The other Steve

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The Cyo is a few lines above the Dosun in the link I posted. Right below the Dosun is the newer Luxos from B&M.

Bandgap said:

You can tap into the Cyo circuits and power its led or the 'main' led.

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Damn thats a good idea. Details?

For those interested, here's my setup.

My carbon fork didn't have a hole in the steerer tube to stick the circuitry (martin's #10) in, so it's ziptied beside the front brake cable (the zipties are taped over because the zipties were clear in colour).



Blue heatsink is out of place, I'll replace them with black ones when it get around to do this.

2 mode front switch.



The SP Dynamo PD-8.



For future upgrades, I have the mounts ready.